If you run one of those demos on Microsoft Windows, you'll see pretty things happening, like calc.exe being launched behind your back.
Both Petko and I said this vulnerability is theoretically cross-platform, but as many reported it couldn't actually be reproduced on Mac OS X.
It doesn't come as a real surprise, though, since this is just another cross-application URI dispatching bug, and the Apple OS has already shown to manage this issue in a much saner way than its counterpart from Redmond.
At any rate, on Windows at least, this can be exploited to do anything the currently logged user can.
Scary, right?